Starting the day sitting third overall at 36 seconds back, tied on time with Orica-Scott's Esteban Chaves, Roche found himself at the back of a rapidly thinning GC group early on the first-category Calar Alto finishing climb with Sky setting a high pace at the front. An attack by Trek-Segafredo's Alberto Contador and Bahrain-Merida's Vincenzo Nibali was the final straw for the Irishman, who came unglued and began losing ground. Teammate Tejay van Garderen lost touch with the leaders as well.

The long, cold trek to the top of the climb ultimately saw Roche cede 4:03 to race leader Chris Froome (Sky), dropping him down to 11th overall.

"There was obviously some very hard racing from the gun as we expected. Today I knew that if the rain was going to continue like that it was always going to be a tough day," Roche said. "It's probably unfortunate that I know myself so well, but even though I tried to always ride on the front, even on the first climb I was struggling. But I fought to stay as much as I could in the front part of the group and then once we hit the last climb and the pace went up my legs were like two blocks of cement."

Considering how much ground he still had left to cover after being dropped, the task of keeping the gap small was always going to be a challenge.

"I had to limit my losses then, obviously it's quite disappointing but that's bike racing, and unfortunately it's happened to me before in the Vuelta," he said. "That was in 2013, I lost six minutes in the end, four minutes this time is not so bad."

Roche will now look to regroup and get back to the strong form that carried him through the first 10 days of racing. While the red jersey will be a tall order now, a top five or even a podium spot may still be in play. The weekend ahead will be another critical test for the 33-year-old.

"The gaps now are starting to be quite consequent. Whereas in the last few days before there was 15 at less than two minutes [on Froome], I don't think there might be too much action tomorrow, but coming into the weekend, the stages into Jaen and Sierra Nevada, for sure the weekend’s going to be really tough and stage 15 is probably with today the Queen stage of the entire race," he said.